There are known so-called exhaust temperature sensors which measure the temperature of exhaust gas flowing through a path such as the inside of a catalytic converter or an exhaust pipe of automobile exhaust emission control device using a thermo-sensitive device.
The thermo-sensitive device whose electric characteristics are sensitive to the temperature is disposed inside a cover. An electric signal produced by the thermo-sensitive device whose electric characteristics are sensitive to the temperature is transmitted through electrode wires to a control device in which the temperature is to be measured.
Such a temperature sensor, as shown in the patent document 1, has the thermo-sensitive device disposed near the catalytic converter or the center of the exhaust pipe to ensure the accuracy in measuring the temperature of gas (maximum temperature) entering the catalytic converter.
The patent document 2 discloses a temperature sensor in which a relation between length of a portion of the temperature sensor protruding into the catalytic converter and length of a platinum resistor to measure the temperature of exhaust gas is specified to measure the temperature accurately and easily.    Patent Document 1: Japanese Patent First Publication No. 2002-350239    Patent Document 2: Japanese Patent First Publication No. 5-79922